CZECH MYCOLOGY 65(2): 157–169, DECEMBER 20, 2013 (ONLINE VERSION, ISSN 1805-1421) First records of Xerocomus chrysonemus (Boletaceae) in the Czech Republic 1 2 3 VÁCLAV JANDA *, MARTIN KŘÍŽ , JIŘÍ REJSEK 1Ondříčkova 29, CZ-130 00 Praha 3, Czech Republic; [email protected] 2National Museum, Mycological Department, Cirkusová 1740, CZ-193 00 Praha 9, Czech Republic; [email protected] 3Poštovská 88, CZ-289 30 Rožďalovice, Czech Republic; [email protected] *corresponding author Janda V., Kříž M., Rejsek J. (2013): First records of Xerocomus chrysonemus (Boletaceae) in the Czech Republic. – Czech Mycol. 65(2): 157–169. The paper details the first collections of Xerocomus chrysonemus in the Czech Republic. The au- thors present a macro- and microscopic description of this species based on the study of material col- lected at five different localities. Characters distinguishing X. chrysonemus from related species of the genus Xerocomus s. str. (X. ferrugineus, X. subtomentosus, and X. silwoodensis) are discussed. The Latin name X. chrysonemus is a combination of the words ‘chryso’ = golden and ‘nema’ = mycelium, which very accurately describes the characteristic feature of this species, the golden yellow mycelium at the base of stipe. Key words: Xerocomus chrysonemus, Boletaceae, description, ecology, Czech Republic. Janda V., Kříž M., Rejsek J. (2013): První nálezy druhu Xerocomus chrysonemus (Boletaceae) v České republice. – Czech Mycol. 65(2): 157–169. Článek informuje o prvních nálezech druhu Xerocomus chrysonemus v České republice. Autoři článku předkládají makroskopický a mikroskopický popis tohoto druhu založený na studiu sbíraného materiálu z pěti různých lokalit. Jsou diskutovány znaky odlišující X. chrysonemus od příbuzných dru- hů rodu Xerocomus s. str. (X. ferrugineus, X. subtomentosus a X. silwoodensis). Latinské jméno dru- hu X. chrysonemus spočívá v kombinaci slov „chryso“ = zlatý a „nema“ = mycelium, což velmi přesně vystihuje jeden z charakteristických znaků tohoto druhu: zlatožluté mycelium na bázi třeně. Navrhujeme pro tento druh české jméno hřib zlatokořenný. INTRODUCTION In August 2011, during a mycological survey of the locality Kněžičky Game Preserve (also known as Žehuňská Game Preserve) in Central Bohemia (Czech Republic), Jiří Rejsek, Josef Šutara and Václav Janda found a fruit body of a small inconspicuous bolete. This bolete resembled Xerocomus subtomentosus (L.: Fr.) Quél., but its basal tomentum was golden yellow and its context was not bluing when cut. After a detailed examination in the following days, Josef Šutara identi- fied this bolete as Xerocomus chrysonemus A.E. Hills & A.F.S. Taylor, a species 157 CZECH MYCOLOGY 65(2): 157–169, DECEMBER 20, 2013 (ONLINE VERSION, ISSN 1805-1421) described from England in 2006 (Taylor & al. 2006). Since then we have focused on obtaining further finds of Xerocomus sp. with the characteristic features of X. chrysonemus. Subsequent study revealed that other collections of this species had also been acquired by other collectors and from other localities, however, this material had often not been satisfactorily identified. The aim of this paper is to inform about our knowledge of the newly observed species X. chrysonemus in the Czech Republic. MATERIAL AND METHODS Macroscopic characters of the bolete described below were studied on fresh fruit bodies growing at several localities, especially within the above-mentioned Kněžičky Game Preserve territory. Some terms in our macroscopical description were used in accordance with the very accurate original description by Hills & Taylor (see Taylor & al. 2006). Microscopic mounts were made from dried mate- rial in ammoniacal Congo Red and Melzer’s solution and studied under an Olym- pus CX21 light microscope. Spore sizes of 20 spores were measured (extremely large spores were omitted) and are presented in the form of the main data range, complemented with extreme values in parentheses. The measurements summa- rise values obtained from fruit bodies from three different localities. The Qav value means the average value of spore length and width ratio. Herbarium specimens have been deposited in the private herbaria of some col- lectors (abbreviations used: JŠ = herb. J. Šutara, VJ = herb. V. Janda), the Mycolog- ical Department, National Museum, Prague (PRM), Museum of Southern Bohe- mia, České Budějovice (CB) and the Museum of Eastern Bohemia, Hradec Králové (HR). Abbreviations of public herbaria follow Thiers (on-line). Data on geological conditions were taken from maps and descriptions at www.geologicke-mapy.cz (Bokr on-line). RESULTS Xerocomus chrysonemus A.E. Hills & A.F.S. Taylor in Taylor, Hills, Simonini, Both & Eberhardt, Mycol. Res. 110(3): 283, 2006. Figs. 1–9 I l l u s t r a t i o n s: Taylor & al. (2006): p. 284 fig. 3A, 3B; Hills (2007): p. 40-42, fig. 22-28; Hills (2008): p. 84, fig. 4; Muñoz et al. (2008): p. 258, fig. A-E; Chalange (2011): p. 286, fig. 15; Kibby (2012): p. 55, fig. 76. 158 JANDA V., KŘÍŽ M., REJSEK J.: FIRST RECORDS OF XEROCOMUS CHRYSONEMUS IN THE CZECH REPUBLIC Description M a c r o s c o p i c c h a r a c t e r s. Pileus at first almost hemispherical, with inrolled margin when young, then convex to pulvinate, 25–50(75) mm wide, yellow-ochre to yellow-olive, greyish tawny, fulvous, often very variable in colour depending on weather conditions, brownish when injured. Pileus surface dry, matt, initially tomentose, becoming glabrous with age. Subcuticular layer of context brownish to red-brown. Tubes 5–10(12) mm long, adnexed to slightly depressed around the stipe and often decurrent with a tooth, initially bright yellow, soon with a greenish tinge, not bluing when cut. Pores bright yellow, golden yellow to amber yellow, usually with a narrow brownish zone at the pileus margin, large (1–2 mm wide) and angular in age, unchanging, not bluing, but after some time slightly browning when bruised. Stipe 30–50(70) × 5–15(20) mm, slender to more or less fairly robust, tapered below, bright yellow when young, resembling the col- our of the pores, soon toning down, finally dull straw with red-brown spots, some- times with an incomplete reticulum forming a stretched net. Stipe base covered with pale yellowish to golden yellow tomentum, basal mycelium golden yellow. Context very pale yellowish white to pale lemon yellow in the pileus, bright yellow in the lower third of the stipe, not turning blue when cut. Taste mild, smell incon- spicuous. M i c r o s c o p i c c h a r a c t e r s. Basidiospores (8)9–12.5(13.5) × (4)4.5–6 μm, Qav = 1.95–2.25, ellipsoid to ellipsoid-fusiform, mostly with suprahilar depression in profile, with distinct hilar appendix, smooth under light microscope, often with one or more oil guttules inside, moderately dextrinoid (becoming pale reddish brown) in Melzer’s solution. Basidia 32–54 × 10–12.5(14) μm, clavate, mostly 4-spored, sterigmata 4–7 μm long. Pleurocystidia 42–62 × 8–11 μm, scattered, smooth and thin-walled, fusiform. Cheilocystidia similar to the pleurocystidia, possibly some- what shorter and thicker. Clamps absent. Hymenophoral trama in fully developed state possessing a bilateral structure with distinctly gelatinised lateral stratum hyphae, but only slightly divergent as in the phylloporoid type. Distance between lateral stratum hyphae variable, frequently up to 5 μm, possibly up to 7(9) μm, but the values are conditioned by precision of the transverse section and are vulnera- ble to the excessive pressure on the cover slip. Distance between mediostratum hyphae is also observable but considerably smaller, up to 1–3 μm. Caulohymenium present, caulocystidia occasionally septate. Pileipellis a trichoderm. H a b i t a t. In damp places covered with rotten leaf litter, moss or grass in oak- hornbeam and oak forests in ectomycorrhizal association with Quercus sp., most commonly with Quercus robur, solitary or in small groups, sometimes even in small clumps comprising two or three fruit bodies. The geological bedrock con- sists of calcareous claystone, marlite and calcareous siltstone, the altitudinal range is from 200 to 260 m a.s.l. 159 CZECH MYCOLOGY 65(2): 157–169, DECEMBER 20, 2013 (ONLINE VERSION, ISSN 1805-1421) Fig. 1. Xerocomus chrysonemus (PRM 861380). A – basidiospores, B – basidia, C – pleurocystidia, D – cheilocystidia (scale bar = 10 μm), E – longitudinal section of hymenophoral trama (scale bar = 100 μm). Del. M. Kříž. 160 JANDA V., KŘÍŽ M., REJSEK J.: FIRST RECORDS OF XEROCOMUS CHRYSONEMUS IN THE CZECH REPUBLIC Fig. 2. Xerocomus chrysonemus, Czech Republic, Kněžičky, Kněžičky Game Preserve, 20 Aug. 2012, under Quercus, leg. M. Kříž (PRM 861379). Photo M. Kříž. Fig. 3. Xerocomus chrysonemus, Czech Republic, Kněžičky, Kněžičky Game Preserve, 10 Sept. 2011, under Quercus, leg. J. Šutara, V. Janda & J. Rejsek (JŠ 5897). Photo V. Janda. 161 CZECH MYCOLOGY 65(2): 157–169, DECEMBER 20, 2013 (ONLINE VERSION, ISSN 1805-1421) Fig. 4. Xerocomus chrysonemus, Czech Republic, Kněžičky, Kněžičky Game Preserve, 15 Sept. 2012, under Quercus, leg. V. Janda & J. Rejsek (VJ150912-01). Photo V. Janda. Fig. 5. Xerocomus chrysonemus, Czech Republic, Kněžičky, Kněžičky Game Preserve, 15 Sept. 2012, under Quercus, leg. V. Janda & J. Rejsek (VJ150912-01). Photo V. Janda. 162 JANDA V., KŘÍŽ M., REJSEK J.: FIRST RECORDS OF XEROCOMUS CHRYSONEMUS IN THE CZECH REPUBLIC Fig. 6. Xerocomus chrysonemus, Czech Republic, Kněžičky, Kněžičky Game Preserve, 10 Sept. 2011, under Quercus, leg. J. Šutara, V. Janda & J. Rejsek (JŠ 5897). Photo V. Janda. Fig. 7. Xerocomus chrysonemus, Czech Republic, Kněžičky, Kněžičky Game Preserve, 1 Oct. 2011, under Quercus, leg. V. Janda & J. Rejsek (VJ011011-02). Photo V. Janda. 163 CZECH MYCOLOGY 65(2): 157–169, DECEMBER 20, 2013 (ONLINE VERSION, ISSN 1805-1421) Fig. 8. Xerocomus chrysonemus, Czech Republic, Kněžičky, Kněžičky Game Preserve, 24 Sept. 2011, under Quercus, leg. V. Janda & J. Rejsek (VJ240911-01).